Field of the Invention
The present invention relates to an exposure apparatus, and a method of manufacturing an article.
Description of the Related Art
There is an exposure apparatus for performing scanning exposure to a shot region on a substrate by scanning slit-shaped light on the substrate as one of the apparatuses used in the manufacturing processes (lithography processes) of semiconductor devices and the like. Such an exposure apparatus performs measurement (focus measurement) of the surface height of the substrate prior to irradiation of the substrate with slit-shaped light, and performs scanning exposure to the shot region while arranging, based on the measurement result, the surface of the substrate on the image plane (focus plane) of a projection optical system.
In the exposure apparatus, a period (settling time) from the completion of acceleration of a stage to the start of scanning exposure may be reduced to increase a throughput. To achieve this, Japanese Patent Laid-Open No. 2009-94256 proposes a method of setting the settling time in accordance with required focus accuracy. For example, if the allowable value of defocus is large, focus measurement in the end portion or the vicinity of a shot region can be omitted. This makes it possible to shorten a period prior to the start of scanning exposure and in which a stage suitable for focus measurement is moved at a uniform velocity, and thus shorten the settling time.
Although the method of setting the settling time in accordance with the allowable value of defocus is effective, defocus may exceed the allowable value depending on the surface shape of a substrate.